The PSSUQ and usability testing


Screenshot of the TryMyUI usability testing platform UX diagnostics dashboard displaying the PSSUQ psychometric

The quantitative usability testing and UX research field is filled with psychometrics that measure the data beyond subjective qualities of users via qualitative means. In fact, our platform provides all the psychometrics that design and research teams could ever want, including the industry standards such as SUS and PSSUQ.

Let’s take a look at PSSUQ specifically.

Screenshot of the TryMyUI usability testing platform’s PSSUQ scoring rubrick

The current iteration of the Post-Study System Usability Questionnaire (PSSUQ) was developed in 1992 by IBM as a means to perform more in-depth system quality and user satisfaction research. The PSSUQ consists of 16 post-test survey prompts that calculate 3 crucial metrics to rate the usefulness of a product. These metrics are:

  • System usefulness

  • Information quality

  • Interface quality


The PSSUQ composite score is a quick reference point for iterative testing, clearly quantifying your design decisions over sprints. The three sub-scores are calculated by the following 16 prompts and can help focus and hone your research into specific areas of improvement.

  • Overall, I am satisfied with how easy it is to use this system.  (Usefulness)

  • It was simple to use this system.  (Usefulness)

  • I was able to complete the tasks and scenarios quickly using this system.  (Usefulness)

  • I felt comfortable using this system.  (Usefulness)

  • It was easy to learn to use this system.  (Usefulness)

  • I believe I could become productive quickly using this system.  (Usefulness)

  • The system gave error messages that clearly told me how to fix problems.  (Information Quality)

  • Whenever I made a mistake using the system, I could recover easily and quickly.  (Information Quality)

  • The information (such as online help, on-screen messages, and other documentation) provided with this system was clear.  (Information Quality)

  • It was easy to find the information I needed.  (Information Quality)

  • The information was effective in helping me complete the tasks & scenarios.  (Information Quality)

  • The organization of information on the system screens was clear.  (Information Quality)

  • The interface of this system was pleasant.  (Interface Quality)

  • I liked using the interface of this system.  (Interface Quality)

  • This system has all the functions and capabilities I expect it to have.  (Interface Quality)

  • Overall, I am satisfied with this system.  (Interface Quality)

Screenshot of the TryMyUI usability testing platform UX diagnostics dashboard displaying the PSSUQ psychometric

Users mark their answers to the 16 items above on a 7-point Likert scale, with 7 meaning “Strongly agree” and 1 meaning “Strongly disagree.” User can also mark the prompts as N/A (not applicable). The UX Diagnostics panel breaks down the performance of each prompt and how each user rated that prompt to help researchers identify their problem areas.

Screenshot of the TryMyUI usability testing platform UX diagnostics dashboard displaying the PSSUQ psychometric

The final result is an individual score for each of the 3 factors that are then averaged into the composite score.

How does PSSUQ differ from other psychometrics?

Put simply, PSSUQ is used to measure perceived satisfaction of a website, app, software, system, or product. It’s questionnaire is longer than most (16 questions), allowing for very nuanced data collection, but could also risk test fatigue. You might think of PSSUQ as a fine-toothed psychometric, used to suss out the finest details after running something like the SUS to uncovered major usability problems.

Here's a list of the other psychometrics on the TryMyUI platform and why PSSUQ might be a better alternative depending on your situation.

SUS:
The System Usability Scale and the PSSUQ are fairy similar, widely-utilized psychometrics. The key difference for deciding between the two comes down to your specific use-case: are you testing a very specific, scenario-based product that you already feel is usable? If so, PSSUQ offers much more nuance than SUS and could be seen as a more specialized version for a more complete product. Take a look at our in-depth comparison: The SUS and PSSUQ: Quantifying user experiences.

ALFQ:
The Adoption Likelihood Factor Questionnaire is meant for early stage development products or to gauge a general interest in the product. While ALFQ does measure some aspects of usability, it isn’t for sophisticated usability and usefulness research in the way that PSSUQ is.

SUPR-Q:
Jeff Sauro’s Standardized User Experience Percentile Rank Questionnaire measures more than just usability or satisfaction, tapping into the heart of the user’s more abstract thoughts of a product such as trust and credibility. One notable consideration is the brand context: SUPR-Q is best utilized for established companies that users are familiar with, and whose designs have already been through rounds of SUS and/or PSSUQ testing to see if the designs are on-brand.

SRS:
The Survey Respondent Scale is the brainchild of a partnership between TryMyUI, MeasuringU, and QuestionPro to address the cognitive stress and fatigue of survey responses on testers. SRS is an extremely specialized metric that is meant more for marketing than usability.

When should I use PSSUQ?

It might be most helpful to ask yourself, “Is my product dependent on a specific scenario? Do I need to know about the quality of information and overall usefulness more than just the usability?

The PSSUQ is the perfect psychometric tool for fine-tuning an already tested product. So, if you and your team are satisfied with your usability scores and now want to know how useful and satisfactory the working flow is, running PSSUQ is absolutely the way to go.

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